Method for treating skin burns



United States Patent 3,198,702 METHGD FOR TREATING SKIN BURNS Arthur A. Hellhaum, 408 W. 57th St., New York, N.Y. No Drawing. Filed Mar. 17, 1960, Ser. No. 15,539 Claims. (Cl. 167-58) This invention relates to compositions and methods for treating skin for the healing of wounds and, more particularly, to the treatment of burned portions of the skin.

Endocrine secretions of the thyroid glands have been recognized as being important to growth and in wound healing. Thyroglobulin, the active principle of desiccated thyroid preparations, is a protein molecule of high molecular weight and is incapable of being absorbed through the skin. When administered orally, it may result in alteration of general body metabolism, with undesirable side reactions. For these reasons, the substance is not favored as medicaments in the treatment of burns even though they possess some indicia of usefulness.

Common burntreatments contain such substances as polyhydric alcohols, viz., glycerine, alkylene glycols, lanolin and the like; but when used in the form of salves, ointments and emulsions for topical treatment, they are deficient in several respects. They do not satisfactorily prevent epidermal hypertrophy nor do they adequately promote regeneration of the epidermis and its appendages.

It therefore becomes an object of the invention to provide a topical-treatment for burned areas of the skin which would be'relatively non-toxic and would be capable 1 of preventing epidermal hypertrophy and would rapidly promote regeneration o fthe epidermis and its appendages.

A further object is to provide a topical burn-treating composition and method which would utilize chemical compounds having healing properties equal or superior,

when applied locally, to desiccated thyroid taken orally and would not be subject to the systemic side effects oc casioned by the oral administration of such desiccated thyroid. Other objects will appear hereinafter.

In accordance with the invention, it has been found that useful compositions for the topical or local treatment of burned areas of the skin may be provided by incorporating with a suitable vehicle a medicative amount of a compound of the formula:

i i o no 4' o 4 6 A 0 l l OR In this formula, at least one X is halogen and the remainder hydrogen; X is hydrogen or halogen. A is a divalent aliphatic radical of from 1 to 5 carbon atoms in chain length, and R may be either hydrogen or a lower alkyl group of from 1 to 3 carbon atoms.

It is preferred to make use of compounds of the type described in which X is iodo and in which at least one X is iodo and the remainder hydrogen; A is a methylene or ethylene radical, and R is hydrogen. Representative of the preferred compounds are iodothyroacetic acids and iodothyropropionic acids, such as triiodothyropropionic acid (3,5,3-triiodothyropropionic acid); triiodothyroacetic acid (3,5,3'-triiodothyroacetic acid), tetraiodothyropropionic acid and tetraiodothyroacetic acid.

While the foregoing represent the prefered group of compounds, other compounds representative of the formula can also be used, such as tetrachlorothyro ethyl acetate, tribromothyroacetic acid (3,5,3'-tribromothyroacetic acid), tetrabromothyro methyl propionate and diiodothyroacetic acid (3,5,-diiodothyroacetic acid).

The compounds described above are suitably combined with a vehicle to form a composition having great value in the treatment of wounds, and particularly burns of all degrees. The vehicles used are preferably selected from alcohols, most preferably, polyhydric alcohols, such as glycerine, the alkylene glycols exemplified by ethylene glycol, 1,3 propylene glycol, 1,2 propylene glycol and the polyoxyalklene glycols formed by the condensation polymerization of ethylene oxide or the propylene oxides. Other less preferred vehicles such as Vaseline, lanolin, paraffin oil, eucerin and myrestinat may also be used.

The vehicles and the compounds can be physically formulated with other suitable substances to produce salves, suspensions, emulsions, ointments, creams, powders, sprays and the like for topical application to the skin. Salves or aerosol sprays are simple to supply and provide a convenient form for utilizing the compounds.

The amount of the compounds added to the vehicle to produce useful burn preparations should be medicative. Best results have been secured utilizing compositions containing about 0.2% by weight of the compoud. Amounts less than .01% are not effective, and amounts greater than 5.0% provide no added benefits. Within the broad range, it is preferred to make use of amounts within the range of 0.13.0%.

For purposes of demonstrating the beneficial results obtained in the practices of the invention, the following is presented by way of example.

White female rats of the Holtzman strain, weighing to 200 grams, were used. A modified burning instrument of the type described in Surgery, vol. 35, pp. 390-400 (1954), with a burning surface 14 mm. in diameter, was employed. Animals were anesthetized with ether, and then burned bilaterally by applying the instrument just posterior to the rib cage and ventral to the spinal muscles. After numerous trials, it was found that a constant second-degree burn could be produced by applying the in strumentfor 2 minutes, with the circulating water at 55.5 C.

A stainless steel screen girdle was placed around the entire trunk of each animal immediately after burning, and before recovery from the anesthetic. The screen fits snugly between the front and hind legs, and prevents licking or scratching of the traumatized area. The open mesh also allows air to reach the wound and also permits ready access for the application to the burned areas of the preparations studied.

Triiodothyroacetic acid, tetraiodothyroacetic acid, triiodothyropropionic acid and tetraiodothyropropionic acid were separately formulated in three different vehicles. The burned area on one side of each animal was treated with the vehicle containing one of the compounds, While the other side received the same vehicle without the compound. Thus each animal carried a direct contralateral control lesion.

The four compounds were each dissolved in a small amount of propylene glycol and thoroughly mixed with the vehicle in a concentration of 0.2%. The three vehicles used were: (1) propylene glycol, 2) an ointment base containing equal parts of lanolin, aquaphor, and polyethylene glycols (Carbowax R 400 and 4,000, a product of Union Carbide Corporation) and an oil-inwater type ointment of the composition:

A. Heat 1, 2, 3 to 60 C., add 4, and stir until dissolved.

B. Heat 6 to 60 C. and dissolve in it. Pour B into A and stir slowly until cooled to room temperature. Fill into l-oz. tin wax-lined tubes.

Initially the burns were treated for periods of 6 to 28 days, and then excised for histological study. It was found that epithelialization of the wounds was invariably complete after 14 days of treatment. Hence, this period of treatment was selected. The sections taken for analysis for cure included both dermis and epidermis. Histological criteria were established in order to evaluate differences in the degree of r covery from burns. This was accomplished by comparing normal unburned skin from the flanks of the rats with skin that had received the standardized second-degree burns, and was still recover- Normal rat skin .has an epidermis 40 micra thick, and 3 cellular layers, 1 cell layer for each stratum (basalis, spinosum and granulosa). The surface may be scaly because of degeneration of the dead cells of the stratum cornium, and may have a slightly rugose appearance.

Numerous hair follicles are seen. The majority are those of the fine hairs, Whose papillae terminate in the connective tissue of the dermis. The large follicles of the larger guard hairs terminate deep in the loose connective tissue of the hypodermis. sebaceous glands are associated with the follicles of the fine hair but not with those of the guard hairs.

The normal dermis is composed of dense irregular connective tissue, with interfibrillar connective spaces about one-half the size of the collagen bundles. The hypodermis between the dermis and skeletal muscles consists of loose areolar connective tissue, and is about the same thickness as the dermis. Vascular structures arborize u-pward from the large vessels in the hypodermis, are distributed to the dermis and to the region adjacent to the epidermis, and around the hair follicles and sebaceous glands. Fibroblasts and other cellular connective tissue inclusions are distributed uniformly throughout the connective tissue zone.

In deep second-degree burns, as produced in this eX- ample, there is complete destruction of the epidermis. The dermis, and sometimes the hypodermis, is destroyed by coagulation necrosis. Thrombosis of the small vessels, and eschar formation from the dead tissue, occurs the full width of the burn. However, this eschar is sloughed off in the course of the healing process.

Re-epithelialization proceeds inward from the healthy tissue at the periphery of the lesion. Epidermal proliferation may also occur outward from the hair papillae if they have not been totally destroyed. Once the healing process has been initiated, a number of stages may be recognized. Epidermal cells move by amoeboid motion in a monocellular sheet from the margins into the defect, but maintain connection with the normal epithelium at .the margins. Only after the advancing epithelium has met that from the opposite margin, and the amoeboid flow has therefore stopped, will the number of cells and hence the number of layers of epidermis increase by mitotic proliferation.

A suitable base for the advancing cells is essential, and consists of compacted fibrin or newly formed fibrous tissue. Nourishment must be allowed to reach the newly formed epithelial cells or they will die and slough off. If the surface is compact and smooth, epithelialization will be rapid. If it is too moist, cells cannot adhere properly and the process of epithelialization is delayed. Sections of skin that have healed following burning may show marked changes in both the epidermis and dermis, but more extensively in the epidermis.

The principal criteria considered to indicate delayed or defective repair of the epidermis were: (1) presence at of thick eschar, 2) denuded surfaces, (3) hypertrophy of epidermis (from 1% to 8 times normal thickness), (4) fiat epidermis (indicating tension forces) and (5) poor regeneration of hair follicles or sebaceous glands.

The following criteria were considered to indicate either delayed or abnormal healing of the dermis: 1) thickening of dermis layer 2 or more times normal, (2) dense thick collagen bundles with small interfibrillar space, (3) infiltration by leucocyte, (4) numerous fibroblasts, indicating repair still in progress, (5) persistence of granulation tissue at dermoepidermal boundary, (6) hypervascularity, and (7) liquefaction of adipose tissue of hypodermis, and collection of vesicular structures, frequently along the line of destroyed and phagocytized hair follicles.

Utilizing the above histological criteria, a scale of relative degrees of healing was established by assigning numerical values to the total defects still apparent in the lesion as compared to the normal unburned skin, which was given the value zero (0). These defect values ranged from 0.0 to 6.0, and were divided into three grades: 0.0 to 2.0, Grade 1, maximum recovery; 2.0 to 4.0, Grade II, and -4.0 to -6.0, Grade III, showing lessening degrees of recovery.

Table I reports the healing effects on burned epidermis of the four thyroXin analogs, in comparison with contralateral control burns receiving only the vehicle without the analog.

Triiodothyropropionic acid was tested on 34 animals. Twenty-six of the treated burns were in Grade I, seven in Grade II, and only one in Grade III. On the other hand, of the control lesions, only 15 were in Grade I, 12 in Grade II, and 7 in Grade III. The chi-square analysis of these groups shows the difference between experimental and control animals to be significant at a P value of 0.05. Tetraiodothyroacetic acid, tested on 33 animals, gave similar results.

The epidermal responses to tetraiodothyropropionic acid and triiodothyroacetic acid were both more pronounced. Forty of the 44 burned areas treated with either of these two analogs were placed in Grade I, whereas only 16 of the untreated control areas were so classified. Statistical analysis of these two groups showed differences to be significant, with P values of 0.01.

The effectiveness of the various analogs differed. Also, the vehicle utilized appeared to influence effectiveness of the analog (results not reported here). Nevertheless, total beneficial effects of the analogs used in this study were significant when compared with the untreated lesions. The totals of Table I show that of the 111 treated lesions, were Grade I, 18 Grade II, and only 3 Grade Ill; whereas of the 111 untreated burns, 45 were Grade I, 47 Grade II, and 19 Grade III. The differences between the total treated and untreated sides were significant at a P value between 0.01 and 0.02.

Table I.Efiects 0f thyroxin analogs 0n burned epidermis compared to contralateml untreated control lesions Table H.-Efiects of thyroxin analogs on burned dermis compared to contralateral untreated control lesions Total No. in Grades Significant Analog N o. of Differences Burn Areas I II III Triiodothyropropionie acid-.. 34 16 17 1 P 0.05 Controls 34 5 21 8 Tetraiodothyropropionic acid- 21 11 9 1 P 0.01 Controls 21 1 16 4 Triiodothyroacetic a 23 12 8 3 P 0.01 Controls 23 2 11 Tetraiodothyroaeetic acid 33 18 10 5 P 0.05 Controls 33 4 19 10 Totals- Treated 111 57 44 10 P 0.01 Controls 111 12 67 32 .As shown in Table II, the iodothyroanalogs also exert beneficial efiects on the healing process of the dermis. The diiferences in the degree of healing between the lesions treated with the various analogs and their untreated counterparts are statistically significant as shown by chisquare analysis. The differences between the treated and untreated burns of the total 111 animals in which the results of the four thyroxin analogs are combined resulted in a P value of 0.01.

All of the thyroxin analogs tested exerted beneficial effects in varying degrees upon Wound healing, Without any observed systemic effects. The two most remarkable effects on healing of burned epidermis were the prevention of epidermal hypertrophy and the promotion of regeneration of the epidermis and its appendages. These two finds were consistently present in every treated burn when compared to its control. Complete epithelialization occurred in the treated burns, on the average, considerably earlier than in the control burns. This beneficial efiect seemed to be due to both an accelerated inward migration of epithelium from the sides of the burns, and an increased growth of epithelium outward from the remaining hair follicles and sebaceous glands. The dermis of the treated burns had less collagen fiber prolifera tion, so that by 14 days after burning, the dermis of the treated burns areas was relatively normal. Compared to this, the dermis of the untreated sides showed an increased proliferation of collagen fibers, both in number and diameter.

This application is a continuation-in-part of my copending application Serial No. 587,964, filed May 29, 1956, and entitled, Composition and Method for Treating Skin Diseases, now abandoned, which was a continuation-in-part of application Serial No. 374,139, filed August 13, 1953, and entitled, Composition and Method for Treating Skin Diseases, now abandoned.

Having thus described my invention, what I claim is:

1. The method of treating burned areas of the skin of animals including humans which comprises applying to said burned areas a composition comprising a vehicle which contains a medicative amount of a compound of the formula:

| OR X X where X is halogen, X' is from the group consisting of halogen and hydrogen, A is lower divalent aliphatic of from 1 to 3 carbon atoms in chain length, and R is from the group consisting of hydrogen and lower alkyl of not more than 3 carbon atoms in chain length.

2. The method of claim 1 where the compound is triiodothyropropionic acid.

3. The method of claim 1 where the compound is tetraiodothyropropionic acid..

4. The method of claim 1 Where the compound is triiodothyroaoetic acid.

5. The method of claim 1 where the compound is tetraiodothyroacetic acid.

6. The method of claim 1 where the vehicle comprises a polyhydric alcohol.

7. The method of claim 2 where the vehicle comprises a polyhydric alcohol selected from the group consisting of glycerine, alkylene glycols and polyoxyalkylene glycols.

8. The method of claim 3 where the vehicle comprises a polyhydric alcohol from the group consisting of glycerine, alkylene glycols and polyoxyalkylene glycols.

9. The method of claim 4 where the vehicle comprises a polyhydric alcohol from the group consisting of glycerine, alkylene glycols and polyoxyalkylene glycols.

'10. The method of claim 5 where the vehicle comprises a polyhydric alcohol from the group consisting of glycerine, alkylene glycols and polyoxyalkylene glycols.

References Cited in the file of this patent Janistyn, Kosmetisches Praktikum, Teil II, Band B (1941), Augsburg, Ziolowsky, pp. 255 and 260-262.

Pitt-Rivers, The Lancet, vol. 265, Aug. 1, 1953, pp. 345-5.

Curme et a1., Chemical and Metallurgical Engineering, vol. 28, No. 4, pp. 169-170, Jan. 24, 1923.

Dumez, Journal or the American Pharmaceutical Association, vol. 28, No. 7, pp. 416-421, July 24, 1939.

Nimrodette, Perfumery and Essential Oil Record, June 1948, pp. 179-183. 1

Ludwig, Repertorium Pharmazeutischer Spezialpraparate, Sera and Impfsoife, 2nd Ed., published by Beobachter, Basel, Switzerland, 1948, page 408.

JULIAN s. LEVITT, Primary Examiner. MORRIS o. WOLK, IRVING MARCUS, Examiner. 

1. THE METHOD OF TREATING BURNED AREAS OF THE SKIN OF ANIMALS INCLUDING HUMANS WHICH COMPRISES APPLYING TO SAID BURNED AREAS A COMPOSITION COMPRISING A VEHICLE WHICH CONTAINS A MEDICATIVE AMOUNT OF A COMPOUND OF THE FORMULA: 